Various food preservation methods are commonly used in order to extend the shelf life of food items. For example, food preservation methods may include refrigeration, high temperature treatment and hermetically sealed containers, water activity (Aw) below a certain level, or pasteurization and acidification to a predetermined pH. Depending on the food type, each food preservation method may have varying results.
Starch products, such as rice, potatoes, and pasta, can use acidification as the preservation method to make them shelf stable. Often, an edible acid, such as lactic or propionic acid, may be introduced to the starch product, thereby lowering the pH of the starch product to a level below about 4.6 or, in some cases, below about 4.2 to render the starch shelf stable. However, the result of acidifying these starchy foods tends to impart undesired organoleptic qualities to the food. In particular, acidified starch products often possess undesirable sour flavor notes attributable to the low pH.
A cheese sauce or cheese-based sauce, on the other hand, often utilizes a preservation system based on water activity, various emulsifying and buffering salts, and a moderate pH between about 5.3 to about 6.2. Shelf-stable cheese sauces, therefore, generally have a higher pH then the acidified starches. Typically, a cheese sauce will include an amount of disodium phosphate that is less than about 3 percent anhydrous by weight. Disodium phosphate is generally used to aid in the manufacture of cheese and cheese sauces by solubilizing protein and facilitating emulsion of fat. Additional disodium phosphate above 3 percent, which is alkaline, tends to increase the pH of the sauce and expected to result in a soapy or metallic flavor.
Given the different preservation systems of cheese sauces and acidified starches, combining the two as a single, shelf stable sauce and starch meal (i.e., sauce and pasta) can be difficult. The different preservation systems of these food components are generally not compatible. When combined, the higher pH of the sauce will tend to increase the pH of the pasta or other acidified starch, which may then destabilize the shelf-stability of the pasta component.
Therefore, it is common to package the acidified food component separate from the sauce component so that each component may be packaged using its desired preservation method. The consumer then mixes the two components together when they are ready to be consumed. When the prior cheese-based sauce component is combined with the acidified pasta component by a consumer, the combined meal can taste too sour generally due to the lower pH of the pasta component, and the flavors achieved with such a combined meal are generally not compatible. Such incompatible flavors tend not to be a problem with meals using acidic sauces, such as tomato-based sauces, because the acidic sauce is more compatible with the acidified starch and tends to mask the undesirable flavor profiles associated with the acidified starch.
Attempts to formulate an acidified starch and cheese-based sauce combination in a shelf stable product that can be combined by a consumer all have various shortcomings that render the meal undesirable for either stability and/or organoleptic reasons. In one approach, the acidified starch can be combined with a neutralizing agent that remains isolated from the acidified food during packaging, but is combined with the acidified starch when the meal is considered ready to eat. One such neutralizing agent is an encapsulated sodium bicarbonate that neutralizes the acid in the starch and results in the creation of salt and carbonic acid, which subsequently breaks down into carbon dioxide and water. Alternatively, the neutralizing agent can be isolated from the starch by being added to a sauce. However, because neutralizing agents such as sodium bicarbonate can also react with both acids and bases, any sauce to which the sodium bicarbonate may be combined with generally needs a pH comparable to sodium bicarbonate; otherwise, the sodium bicarbonate could react with the sauce to form undesirable salts, water and/or carbon dioxide. Such reactions may affect the organoleptic qualities of the sauce and may adversely affect the packaging of the sauce.
U.S. Pat. No. 7,189,423 to Irwin et al. describes the addition of increased amounts of edible alkaline or base substances to a sauce for later combination with acidified starch products. The resultant sauce, therefore, has an increased pH between about 6.2 and about 7.2. The sauces of Irwin, therefore, when combined with the acidified starch, have a sufficiently high pH to generally increase the pH of the starch to levels that exhibit more traditional flavor notes. However, the increased pH of Irwin's sauce, on the other hand, is outside the pH range generally desired for shelf-stable cheeses and may render the preservation system less effective and/or negatively impact the organoleptic qualities of the sauce because the pH is increased beyond the expected normal ranges (i.e., about 5.3 to about 6.2) for a traditional cheese based sauce.